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SubjectRe: [PATCH v2] device-dax: use fallback nid when numa node is invalid
On Mon, Sep 13, 2021 at 7:06 PM Justin He <Justin.He@arm.com> wrote:
>
> Hi Dan,
>
> > -----Original Message-----
> > From: Dan Williams <dan.j.williams@intel.com>
> > Sent: Friday, September 10, 2021 11:42 PM
> > To: Justin He <Justin.He@arm.com>
> > Cc: Vishal Verma <vishal.l.verma@intel.com>; Dave Jiang
> > <dave.jiang@intel.com>; David Hildenbrand <david@redhat.com>; Linux NVDIMM
> > <nvdimm@lists.linux.dev>; Linux Kernel Mailing List <linux-
> > kernel@vger.kernel.org>
> > Subject: Re: [PATCH v2] device-dax: use fallback nid when numa node is
> > invalid
> >
> > On Fri, Sep 10, 2021 at 5:46 AM Jia He <justin.he@arm.com> wrote:
> > >
> > > Previously, numa_off was set unconditionally in dummy_numa_init()
> > > even with a fake numa node. Then ACPI sets node id as NUMA_NO_NODE(-1)
> > > after acpi_map_pxm_to_node() because it regards numa_off as turning
> > > off the numa node. Hence dev_dax->target_node is NUMA_NO_NODE on
> > > arm64 with fake numa case.
> > >
> > > Without this patch, pmem can't be probed as RAM devices on arm64 if
> > > SRAT table isn't present:
> > > $ndctl create-namespace -fe namespace0.0 --mode=devdax --map=dev -s 1g
> > -a 64K
> > > kmem dax0.0: rejecting DAX region [mem 0x240400000-0x2bfffffff] with
> > invalid node: -1
> > > kmem: probe of dax0.0 failed with error -22
> > >
> > > This fixes it by using fallback memory_add_physaddr_to_nid() as nid.
> > >
> > > Suggested-by: David Hildenbrand <david@redhat.com>
> > > Signed-off-by: Jia He <justin.he@arm.com>
> > > ---
> > > v2: - rebase it based on David's "memory group" patch.
> > > - drop the changes in dev_dax_kmem_remove() since nid had been
> > > removed in remove_memory().
> > > drivers/dax/kmem.c | 31 +++++++++++++++++--------------
> > > 1 file changed, 17 insertions(+), 14 deletions(-)
> > >
> > > diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
> > > index a37622060fff..e4836eb7539e 100644
> > > --- a/drivers/dax/kmem.c
> > > +++ b/drivers/dax/kmem.c
> > > @@ -47,20 +47,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
> > > unsigned long total_len = 0;
> > > struct dax_kmem_data *data;
> > > int i, rc, mapped = 0;
> > > - int numa_node;
> > > -
> > > - /*
> > > - * Ensure good NUMA information for the persistent memory.
> > > - * Without this check, there is a risk that slow memory
> > > - * could be mixed in a node with faster memory, causing
> > > - * unavoidable performance issues.
> > > - */
> > > - numa_node = dev_dax->target_node;
> > > - if (numa_node < 0) {
> > > - dev_warn(dev, "rejecting DAX region with invalid
> > node: %d\n",
> > > - numa_node);
> > > - return -EINVAL;
> > > - }
> > > + int numa_node = dev_dax->target_node;
> > >
> > > for (i = 0; i < dev_dax->nr_range; i++) {
> > > struct range range;
> > > @@ -71,6 +58,22 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
> > > i, range.start, range.end);
> > > continue;
> > > }
> > > +
> > > + /*
> > > + * Ensure good NUMA information for the persistent
> > memory.
> > > + * Without this check, there is a risk but not fatal
> > that slow
> > > + * memory could be mixed in a node with faster memory,
> > causing
> > > + * unavoidable performance issues. Warn this and use
> > fallback
> > > + * node id.
> > > + */
> > > + if (numa_node < 0) {
> > > + int new_node =
> > memory_add_physaddr_to_nid(range.start);
> > > +
> > > + dev_info(dev, "changing nid from %d to %d for
> > DAX region [%#llx-%#llx]\n",
> > > + numa_node, new_node, range.start,
> > range.end);
> > > + numa_node = new_node;
> > > + }
> > > +
> > > total_len += range_len(&range);
> >
> > This fallback change belongs where the parent region for the namespace
> > adopts its target_node, because it's not clear
> > memory_add_physaddr_to_nid() is the right fallback in all situations.
> > Here is where this setting is happening currently:
> >
> > drivers/acpi/nfit/core.c:3004: ndr_desc->target_node =
> > pxm_to_node(spa->proximity_domain);
> On my local arm64 guest('virt' machine type), the target_node is
> set to -1 at this line.
> That is:
> The condition "spa->flags & ACPI_NFIT_PROXIMITY_VALID" is hit.
>
> > drivers/acpi/nfit/core.c:3007: ndr_desc->target_node =
> > NUMA_NO_NODE;
> > drivers/nvdimm/e820.c:29: ndr_desc.target_node = nid;
> > drivers/nvdimm/of_pmem.c:58: ndr_desc.target_node =
> > ndr_desc.numa_node;
> > drivers/nvdimm/region_devs.c:1127: nd_region->target_node =
> > ndr_desc->target_node;
>
>
> Sorry,Dan. I thought I missed your previous mail:
>
> =========================================
> Looks like it is the NFIT driver, thanks.
>
> If you're getting NUMA_NO_NODE in dax_kmem from the NFIT driver in
> means your ACPI NFIT table is failing to populate correct numa
> information. You could try the following to fix it up, but I think the
> real problem is that your platform BIOS needs to add the proper numa
> data.
>
> diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> index fb775b967c52..d3a0cec635b1 100644
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -3005,15 +3005,8 @@ static int acpi_nfit_register_region(struct
> acpi_nfit_desc *acpi_desc,
> ndr_desc->res = &res;
> ndr_desc->provider_data = nfit_spa;
> ndr_desc->attr_groups = acpi_nfit_region_attribute_groups;
> - if (spa->flags & ACPI_NFIT_PROXIMITY_VALID) {
> - ndr_desc->numa_node = acpi_map_pxm_to_online_node(
> - spa->proximity_domain);
> - ndr_desc->target_node = acpi_map_pxm_to_node(
> - spa->proximity_domain);
> - } else {
> - ndr_desc->numa_node = NUMA_NO_NODE;
> - ndr_desc->target_node = NUMA_NO_NODE;
> - }
> + ndr_desc->numa_node = memory_add_physaddr_to_nid(spa->address);
> + ndr_desc->target_node = phys_to_target_node(spa->address);
>
> /*
> * Persistence domain bits are hierarchical, if
> ===================================================
>
> Do you still suggest fixing like this?

Are you saying that ACPI_NFIT_PROXIMITY_VALID is not set on your
platform, or that pxm_to_node() returns NUMA_NO_NODE?

I would expect something like this:

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index a3ef6cce644c..95de7dc18ed8 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -3007,6 +3007,15 @@ static int acpi_nfit_register_region(struct
acpi_nfit_desc *acpi_desc,
ndr_desc->target_node = NUMA_NO_NODE;
}

+ /*
+ * Fallback to address based numa information if node lookup
+ * failed
+ */
+ if (ndr_desc->numa_node == NUMA_NO_NODE)
+ ndr_desc->numa_node = memory_add_physaddr_to_nid(spa->address);
+ if (ndr_desc->target_node == NUMA_NO_NODE)
+ phys_to_target_node(spa->address);
+
/*
* Persistence domain bits are hierarchical, if
* ACPI_NFIT_CAPABILITY_CACHE_FLUSH is set then
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